In high-quality assemblies subjected to considerable stress for extended periods, for example aircraft structure assemblies, methods have been known for a relatively long time for using attachments in two parts comprising a rod on which a ring is crimped.
One example of such an attachment is depicted in FIG. 1 installed to allow the assembly, for example, of two panels 16 and 17.
The attachment 1 comprises, on the one hand, a substantially cylindrical rod 11 with a longitudinal axis 10 ending in a head 12 at one end. At the end of the rod 11 opposite the head 12 the rod comprises a series of grooves 13 along part of its length. The overall length of the rod is selected according to the thickness of the assembled panels so that, when the rod is in place in an attachment hole passing through the two panels and the head 12 of the rod 11 is resting against one surface of the panel 16 on the side of said head, the length of the rod comprising the grooves 13 sticks out from the panel 17 on the side opposite the head 12.
The attachment 1 comprises, on the other hand, a ring 15 which is resting against the free surface of the panel 17, the material of which adapts to the shape of the grooves 13 so that the attachment firmly holds the two panels 16 and 17 together due to the pull exerted on the rod 11 between the head 12 and the ring 15.
Such an attachment is described, for example, in U.S. Pat. No. 2,531,048.
The usual way of installing this type of attachment involves a tool that first exerts a pull on the rod 11, for example by means of an extension 18 of the rod on the side of the end opposite the head 12, taking support on the free surface of the panel 17 next to the attachment 1, and then crimps the ring 15 previously slipped onto the rod 11, radially compressing said ring, made from a ductile material, on the grooves 13 so that the material of the ring adapts to the shapes of the grooves.
In a third instance, the pull on the rod 11 is released and the tool is removed. In most cases, this step includes breaking the extension 18 of the rod at a calibrated breakage area 19, said extension having no further utility when the attachment is in place.
As can be seen from the description of this process, the installation of an attachment therefore requires several consecutive operations.
When the hole in which the attachment is to be installed is made, it is necessary to:                place the rod 11 in the hole via one surface of the assembly;        slide the ring 15 onto the rod on the side of the other surface of the assembly;        position the crimping tool;        crimp the ring 15 by exerting a pull on the extension 18 of the rod 11;        remove the tool.        
When this sequence must be performed many times, several hundred or several thousand times, for example during the assembly of complex structures such as aircraft structures, any reduction of the time required for each installation cycle becomes particularly important for reducing assembly times and inherent costs.
Evidently, the time required for each attachment installation cycle, which is to say, positioning the tools and installing the actual attachment, can only be reduced to the detriment of the quality of the assemblies.